2007年12月26日 星期三

A previously healthy 22-year-old man presented with a 3-month history of intermittent abdominal pain and hypochromic microcytic anemia, with a hemoglobin level of 5.1 g per deciliter and a mean corpuscular volume of 75 µm3. Initial endoscopy of the upper and lower gastrointestinal tract was unremarkable, despite a positive test for fecal occult blood. Further investigation with video-capsule enteroscopy showed an intraluminal bulge within the proximal jejunum 77 minutes after ingestion of the capsule. Six days later, the patient presented with abdominal pain, nausea, and vomiting. Computed tomography showed the presence of an intussusception (arrow). On emergency laparotomy, a proximal jejunojejunal intussusception was found and resected. Pathological examination revealed that the leading edge of the intussusception was a pedunculated benign lipomatous polyp. At a follow-up visit 2 months later, the patient was free of pain and had no further signs of bleeding.

ICDs: Not a Cure for VT or VFPatients with a history of myocardial infarction who survive a spontaneous episode of ventricular arrhythmia are at high risk for subsequent sudden death from recurrent ventricular tachycardia or ventricular fibrillation. Implantable cardioverter-defibrillators (ICDs) decrease mortality and have, therefore, become the mainstay of treatment. However, ICDs are not a cure for ventricular arrhythmias. Defibrillator discharges (shocks) for treatment of recurrent arrhythmias are painful, and syncope may occur before delivery of therapy.

Catheter-Based Mapping and Ablation TechniquesCatheter-based mapping and ablation techniques represent nonpharmacologic methods for the treatment of ventricular tachycardia. The most common indication for radiofrequency ablation is ventricular tachycardia refractory to drug therapy in patients with coronary artery disease that results in frequent shocks from an ICD. However, only 5 to 10% of patients with coronary artery disease show sufficient hemodynamic stability to allow identification of target sites with catheter-based mapping during an episode of ventricular tachycardia. This limitation thus sharply constrains the clinical application of catheter ablation.

Q: What is an 『ICD storm?』A: An 『ICD storm』 is the term used to describe repeated ICD (implantable cardioverter-defibrillator) shocks delivered within a short time interval. These events occur in 10 to 25% of patients with implantable cardioverter-defibrillators. Clinically significant anxiety and depression as a result of recurrent ICD shocks may occur in more than 50% of patients.

重點：Lactate converts to bicarbonate in liver. Patients with lactic acidosis usually have inadequate liver metabolism of lactate so conversion to HCO3- from the infused lactate of LR is impaired and may give false readings of serial lactate measurements but may be a better choice in regular situations where hyperchloremia restricts use of normal saline.

2007年12月12日 星期三

Procedure: Central Venous CatheterizationThe placement of a central venous catheter is indicated for the continuous monitoring of central venous pressure and for the delivery of critical or caustic medications.

Complications of Central Line PlacementSpecific complications associated temporarily with placement of a subclavian line include hemothorax and pneumothorax, air embolism, inadvertent arterial puncture, and aortic perforation. Obtain a chest radiograph after placement to assess for complications and to confirm correct placement of the catheter. Common malplacement locations include placement transverse to the contralateral subclavian vein, retrograde into the ipsilateral internal jugular vein, or potentially the contralateral internal jugular vein.

Guidelines to Decrease Risk of InfectionThe Institute for Healthcare Improvement has developed specific guidelines to help decrease the risk of infection in patients with central venous catheters. The guidelines include the use of proper hand hygiene, the use of maximal barrier precautions during placement, the use of chlorhexidine skin antisepsis, and daily review of the need for the catheter.

Morning Report QuestionsQ: In what position should a patient be placed in for insertion of a central line in the subclavian vein? Does the use of a rolled towel under the spine increase or decrease the size of the subclavian vein?A: A patient who is undergoing placement of a central line in the subclavian vein should be placed in a 15-degree Trendelenburg position. If you place a rolled towel or similar object under the spine to help identify the patient's external landmarks, be aware that propping the shoulder or turning the head has been shown to decrease the size of the vein on ultrasonography.

Q: What are general contraindications for placement of a central venous catheter?A: General contraindications for placement of a central venous catheter include infection of the area overlying the target vein and thrombosis of the target vein. Specific contraindications to the subclavian approach include fracture of the ipsilateral clavicle or anterior proximal ribs, which can distort the anatomy and make placement difficult. Greater caution should be used when placing a central venous catheter in coagulopathic patients. The location of the artery (beneath the clavicle) makes application of direct pressure nearly impossible in attempts to control bleeding.

2007年12月9日 星期日

Peutz–Jeghers syndrome is an autosomal dominant disorder caused by a germ-line mutation of the serine/threonine kinase 11 (STK11) gene. Hamartomatous polyps, the hallmark of the disorder, are seen in 88% of all patients. Pigmented mucocutaneous lesions are present in nearly all patients by 2 years of age and most commonly occur on the lips and perioral region, followed by the hands, buccal mucosa, and the feet. The most frequent complication of polyps is intussusception. Patients with Peutz–Jeghers syndrome are also at high risk for intestinal and extraintestinal cancer. The most common cancers are gastrointestinal and breast.

Morning Report Question

Q: What are some causes of intussusception in adults?

A: Causes of small-intestinal intussusception in the adult population include tumors, foreign bodies, unusual endoluminal infections such as ascariasis — and endometrial implants (in females). Of note, only 5% of intussusceptions occur in adults. An underlying cause of intussusception is identified in 90% of adults. Benign and malignant neoplasms account for the majority of cases.